1. Field of the Invention
The invention concerns a device for branching gas flows, particularly in a gas chromatograph.
2. Background Art
In the field of gas chromatography it is known to place gas flow diverters in the flow path between two or more chromatography separating columns in order to enable the flow from a separating column to go at choice to one or more subsequent separating columns or detectors. In the known systems of this kind, the flow direction is diverted by the presence of auxiliary flow paths by means of which a positive pressure is produced in the particular branches it is required to close. The principle of this form of flow diversion is described in German patent 1,811,860. German patent specifications Nos. 2,806,123, 2,655,387 and 2,840,612 disclose other flow diverters based on the same principle.
It is a main purpose of these systems to be able to divert the flow direction without any contact occurring between the gas flow being controlled and valves. The point is that gas flows usually contain constituents which may be deposited in the valves. This may lead to two results--the valves become unserviceable, and the original gas flow composition is altered, thus falsifying the quantitative and qualitative determination of the substances present in the gas flow. Some of the known systems dealt with the problem of simplifying the complicated valve systems made necessary by the use of auxiliary flows. Nevertheless, all the known systems have disadvantages. For example, the auxiliary flows introduce impurities into the system and the flow dividers are of fairly complex construction requiring a considerable outlay for valves and valve controls.
It is an object of the present invention to simplify considerably the branching of gas flows.